Method of uniting metals.



W. D. COOLIDGE.

METHOD OF UNITING METALS.

APPLICATION FILED MAR. 4. 1914 Patented Nov. 30, 1915.

Witnesses: mx%m.

. Uniting Metals,

amino so e rarnn'r clar on.

WILLIAM D. COOLIDGE, OF SCHENECTADY, NEW YORK, ASSIGN'OR T0 GENERAL ELECTRIC COMPANY, A'CORPOBATION OF NEW YORK.

METHOD OF UNITING- METALS.

Specification of Letters Patent.

Patented Nov. 30, 1915.

Original application filed March 20, 1912, Serial No. 685,113. Divided and this application filed March 4,- 1914. Serial No. 822,250. v v 1 'To all whom it may concern:

Be it known that I. WILLIAM D. Coomocn, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Methods of (division of my application Serial .l o. 685,113, filed March 20,1912,) of which the following is a specification. I My invention comprises a method of oining or soldering' tungsten to other metals, so as to obtain most intimate strong m'echanical junction which will therefore have the best electrical and heat conductivity.

Tungsten cannot be joined satisfactorily to other metals by soldering in the ordinary manner. This difficulty is apparently due to the ease with which a thin film of oxid forms on the surface of the tungsten. The soldering metal either will not stick or when apparent adhesion has been produced I find that when subjected to any strain the soldering metal breaks away as though the tungsten broke away from the film of oxid.

My invention relates broadly to a method of joining or soldering tungsten either for contacts or for any other purpose tocopper, to form a unitary structure.

In the accompanying drawings, Figure 1 showsa body of copper cast directly into contact with apiece of tungsten; and Fig. 2

shows a machined contact attached to a support.

In carrying out the process, I find it highly desirable to completely remove from the surface of the tungsten body all the loosely adherent metalor oxid which I find is left by the preliminary process of shaping the tungsten. Unless this is done, I find that in some cases the tungsten may be torn away from its backing or support at this loosely adherent surface layer, part of which willbe found clin ing to the copper or other metal used as so derl- In order to remove this surface layer I prefer to bring the body of tungsten into contact with melted nitrite of sodium or potassium for a few seconds or is caused to unite autogenically with a tungsten body by heating to a temperature cons derably above the melting point of copper 1n a vacuum preferably to a temperature about 1100 deg. C. Under these conditlons an oxid of tungsten cannot exist, the oxid at this temperature being dissociated into metallic tungsten and oxygen. The copper itself appears to lose at least part of its dissolved gases.

The operation may be carried out by placing a body of tungsten and a quantity of copper in a crucible, as shown in Fig. l, and heating the crucible and its contents in a vacuum furnace such as shown in Arsem Patent No. 785,535. After being heated to the required temperature the copper and tungsten are simply allowed to cool in contact with each other. Upon removal from the crucible, the copper may be machined.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. The method of promoting the adhesion or wetting of molten copper to the surface of a body of tungsten which consists in heating said copper in contact with the tungsten in a vacuum at a temperature materially above the melting point of copper.

2. The method of promoting the adhesion or wetting of molten copper to the surface 3. The method of producing .a composite metal body, one of the metals being copper In Witness whereof, I have hereunto set and the other tungsten, \vhloh conslsts 111 51- my hand thls 27th day of February 1914. multaneously heatmg the copper 1n contact 1 with the tungsten body in a vacuum at a IILLIAM (JOOLIDGE 5 temperature materially above its melting 'itnesses:

point and allowing the copper to solidify IIELEN Olwom),

in :rvacuum. MARGARET E. WOOLLEY. 

